Starting Out With Java: Chapter 2

Front 1

List some rules one might use in programming languages.

Back 1

• Keywords, and Syntax
• Statements that carry out pre-determined logic
• Variables
• Programmer-defined names
• Operators
• Data Structures

Front 2

What are the two types of classes?

Back 2

1. Application Class: think of this as the means by which the flow of the application is controlled
2. Classes that represent objects: Think of this as a blueprint of a type of object or “thing” that is represented in our application

Front 3

What does a class include?

Back 3

• A data section
• A method section
• It does NOT execute on its own
• It provides all the code to create objects with similar characteristics (attributes) and similar behaviors (actions)

Front 4

Why is Java so important?

Back 4

Java can be coded to run the same on all platforms. Because it runs on all platforms, JAVA is the language used to develop code for web and mobile devices.

Front 5

What are the requirements for a Java Application?

Back 5

It must contain a “main” method, and it may contain other java classes.

Front 6

What are the two ways a Java program can be written and what are their functions?

Back 6

1) An Applet – a Java program designed to run in a Web page

2) An application – a Java program designed to run anywhere

Front 7

What do other classes need?

Back 7

Some classes are provided in the JAVA language, but other classes you need to define yourself.

Front 8

Can a Java program be composed of one or more classes?

Back 8

Yes, all JAVA programs are composed of one or more JAVA classes.

Front 9

What is the first step in a basic Java Application?

Back 9

We always start the application class source:

public class classname

Front 10

What does Public mean?

Back 10

Whatever you are making public is available to other classes.

Front 11

What does Static mean?

Back 11

An object doesn’t need to be instantiated to use the method.

Front 12

What does Void mean?

Back 12

The method doesn’t return anything.

Front 13

What are arguments?

Back 13

Data the method or statement needs to do its job, found in parentheses.

Front 14

How do you end most Java statements?

Back 14

All Java statements end in a semi-colon.

Front 15

What does System.out.print() do for your code?

Back 15

Prints whatever is within quotes in the parentheses on one line of output.

Front 16

What does System.out.println() do for your code?

Back 16

Prints whatever is within quotes in the parentheses on one line of output and then puts the cursor at the start of the next line.

Front 17

Where do we get System from?

Back 17

From the Java API package java.lang

Front 18

What is ‘out’ referred to as?

Back 18

out is an attribute (often called Instance Variable) of the class.

Front 19

What do print() and println() represent?

Back 19

print() or println() are methods of the system class.

Front 20

Why is the java.lang package so significant?

Back 20

Any class from the java.lang package can just be used directly in your code without doing anything special first.

Front 21

What is an escape sequence?

Back 21

A backslash followed by a character that has special meaning to the compiler. They are used to complete an action when there is no other way to do it.

Front 22

String literals must be enclosed in what?

Back 22

Double quotes:

“String Literal”

Front 23

What do we use to print two different strings and what is the name of the procedure?

Back 23

We use the string concatenation operator +

Front 24

What is a literal?

Back 24

Any string, number, or character that can be written into a program, and that we want to program use to generate the intended result.

Front 25

What is a variable?

Back 25

A space in the computer’s memory that we reserve to hold specific data.

Front 26

What are the specific rules that must be followed with all identifiers?

Back 26

• Should have a meaningful name
• Must begin with a letter, an underscore, or a dollar sign.
• The remaining characters can be letters, digits, underscores, or dollar signs.
• Cannot contain spaces
• Case sensitive.

Front 27

Can a variable hold more than one value?

Back 27

A variable cannot hold more than one value at one time. If you declare a variable, the value can change, but it cannot be 2 values at once.

Front 28

What is the priority of math operators?

Back 28

1. ()
2. *, /, %
3. +, -
4. <, <=, >, >=

Front 29

What package do we get the Math Class from?

Back 29

java.lang

Front 30

What is the rank of data types?

Back 30

1. double
2. float
3. long
4. int
5. short
6. byte

Front 31

Can we force a conversion and if we can how?

Back 31

We can “force” the conversion in either direction by casting.

Front 32

What are constants and how do we code them?

Back 32

Constants are like variables, but their values never change. We declare them by using the final keyword:

final double MINI_BLIZZARD = 2.70

Front 33

What does a class contain?

Back 33

Each class has a name, attributes called instance variables, and methods.

Front 34

Where can we acquire classes?

Back 34

Some classes are part of the JAVA API, but others we get from JAVA libraries or we create ourselves.

Front 35

What are classes considered to be?

Back 35

Classes are considered to be a reference data type.

Front 36

What is a reference data type?

Back 36

A reference data type assigns the memory address of that String object to the variable.

Front 37

What does Length do?

Back 37

Provides the length of a string object.

Front 38

What type of statement do we need to use classes from other packages?

Back 38

We need an import statement.

Front 39

Who do I request a Scanner in a program?

Back 39

The Scanner class is used to get data into the program. We can use the same Scanner object for different input in our program.

Front 40

What is the difference between a Class Name and *, and which one is better?

Back 40

A class name says that we will use the certain class from the package. The * means that we will use multiple classes from the same package. The class name is better when using less than 3 classes. Be careful of the memory recourses when using *.

Front 41

How do we create a Scanner?

Back 41

Scanner keyInput = new Scanner(System.in);

Front 42

What can we use to get the data from the Scanner to the variable? Name a few.

Back 42

Scanner Methods:
nextByte()
nextDouble()
nextFloat()
nextInt()
nextLine()
nextLong()
next Short()

Front 43

Is there a difference for a Char versus a String?

Back 43

Yes, to allow a char you need to do something like this:
String gradeAsString;
char grade;
gradeAsString = keyInput.nextLine();
grade = keyInput.charAt(0);

Front 44

Should we accept a String or a number first?

Back 44

Try to accept a string first, but if you need to accept the number first, remember to run an extra “nextLine()” method between the number and the string.

Front 45

What is a different way to read information (not Scanner)?

Back 45

JOptionPane

Front 46

How do I request a JOptionPane?

Back 46

import javax.swing.JOptionPane;

Front 47

Name two Dialog boxes that you can use.

Back 47

Message Dialog
Input Dialog

Front 48

How do I code a Message Dialog Box?

Back 48

JOptionPane.showMessageDialog(null, ”Phrase”)

Front 49

Why do I need a null?

Back 49

Null is the default argument used when you are displaying contents in different windows.

Front 50

Is there a catch to using a Dialog box?

Back 50

It only returns the user input as a string.

Front 51

As a programmer how do I get around the Dialog Box catch?

Back 51

Convert To String Using:
Byte.parseByte(string Variable)
Double.parseDouble(string Variable)
Float.parseFloat(string Variable)
Integer.parseInteger(string Variable)
Long.parseLong(string Variable)
Short.parseShort(string Variable)

Front 52

What does Decimal Format do?

Back 52

One way to format floats and doubles.

Front 53

What is the preferred way to code an output with decimals?

Back 53

Printf method